Light sensitive diazo sulfonate material and preparation of printing plates therewith



United States Patent Ofiice 3,168,401 Patented Feb. 2, 1965 3,168,401 LIGHT SENETIVE DEAZO SULFGNATE MATERZAL AND PREPARATION OF PTWG PLATE THEREWITH Oskar Sus, Wiesbaden-Biebrich, Germany, assignor, by mesne assignments, to Azoplate Corporation, Murray Hill, NJ. No Drawing. Continuation of application Ser. No.

685,408, Sept. 23, 1957.. 1963, Ser. No. 298,427 Claims priority, application Germany, June 18, 1954, K 22,579 3'2 Claims. (Cl. 96-33) The present invention relates to the production of light-sensitive material suitable for use in the graphic arts. More particularly, it relates to the manufacture of lithographic printing plates and to light-sensitive material suitable therefor.

It has previously been suggested to prepare presensitized lithographic printing plates using certain water-soluble and water-insoluble diazo compounds as the light-sensitive substance.

It is an object of this invention to provide still another group of diazo compounds of this type which are characterized by excellent storageability while having a simple chemical constitution. A further object of the invention is the use of certain diazo sulfonates in light-sensitive material which become colored upon exposure to light without the previous addition of dyestuffs or azo components.

The light-sensitive material, according to the present invention, is characterized in that its light-sensitive layer consists of diazo sulfonates of cyclic amines (aromatic as well as heterocyclic) in which the salt-forming cationic component is an aromatic, hydroaromatic or heterocyclic amine with a primary amino group.

It is believed that the light sensitive material of the present invention owes its excellent storageability to the fact that the diazo sulfonates have stability which exceeds that of other diazo compounds. As a further advantage deriving from the greater stability of the light sensitive substances of the present invention, it is now found to be more convenient to handle the new light sensitive material as well as the diazo sulfonates in manufacturing the new material.

The diazo sulfonate derivates constituting the lightsensitive layer, in accordance with the present invention, are prepared by means of an exchange of the cation of an alkali-metal diazo sulfonate with an organic primary base, according to the following reaction scheme:

R and R are aryl, substituted aryl or heterocyclic radicals, and X is the anion of an acid.

There are a great number of diazo sulfonates conforming to the expression R--N=N SO Na which may be considered for the preparation of the diazo sulfonate derivatives to be used as light-sensitive substances according to the present invention. With regard to the usefulness of the printing plates prepared from the light sensitive metal foils, it is preferred that the diazo sulfonates RN=NSO Na contain neither strongly basic groups nor groups that render them water-soluble, such as SO H or COGH. Furthermore, the degree of light sensitivity and the stability of the diazo sulfonates RN=N-SO Na should also be considered. The better their light sensi- This application July 29,.

tivity and their stability, the better is the light sensitivity and stability of the diazo sulfonate derivativeswhich are obtained therefrom.

In general, the diazo sulfonates of the following compounds have proved useful: amino carbazoles, amino-diphenylene-oxides; 4-amino-diphenyl-amine, p-phenylenediamines that are acylated at a nitrogen atom and alkoxylated in their aromatic nucleus; and mono-amino compounds of alkoxylated diphenyland triphenylmethane.

As the salt-forming organic base having the general formula H N-R preferably the primary amines of multinuclear compounds are used, because these amines are well suited to decrease the water solubility of the reaction products. Polyamino compounds, such as benzidine, dianisidine, diamin-diphenyl-methane, and triamino-toluol, have a special capacity for decreasing the water solubility of the reaction product when reacted with the alkali metal salts of diazo sulfonates. In the salts thus obtained, as many moles of the diazo compound, e.g. 2 or 3, are linked via the residue of the sulfonic acid to one mol of the base as there were amino groups previously contained in the base. Another method of preparing the diazo sulfonates of the present invention consists in causing the alkali-sulfonate of a tetrazo compound to react with 2 moles of an aromatic amino salt.

A metal is used as a support for the compounds of the present invention, preferably aluminum. It is not necessary to subject the metallic surface to an anodic oxidation or to a chemical treatment before coating it. However, it may be advantageous to roughen the surface by a simple mechanical treatment, e.g. sandblasting.

For the preparation of the light-sensitive material, the diazo sulfonate derivatives RN=N4O H-H NR are dissolved in organic solvents, such as alcohols, alcoholic ethers, dioxane, or dimethyl formamide, and the solutions are then coated onto the support by way of whirlcoating, spreading, or spraying. The resulting layers must be well dried, preferably at temperatures between -1 10 C. As a rule, the dried layers are yellow colored. They are, when dry, exposed to light under a transparent original, using one of the light sources customary in the printing art, preferably an arc lamp. Under the influence of light, the light struck areas of the layer change color; they turn yellow-brown to deep blue, depending on the respective sulfo'nate derivate used. It may be advisable to add alkali-soluble phenol formaldehyde resin, rosin, or shellac, as these additions favor the formation of a smooth layer on the support and prevent crystallization of the light-sensitive substance in the layer.

The finished printing plate is obtained from the exposed foil by treating it with dilute aqueous solutions of alkaline substances, preferably of secondary or tertiary alkali metal salts of phosphoric acid, sodium carbonate, or sodium bicarbonate. Concentrations of 110% of the alkali metal salts have proved especially suitable. By this treatment, the unchanged light sensitive substance is removed, whereas the light decomposition product remains on the plate. From a negative original a colored positive image is obtained, which is clearly visible against the metallic background with a good contrast. Since the light decomposition product has oleophilic properties, the image may be inked with greasy ink after a short rinsing with water, dilute acids, or the usual acid fixing agents. In some cases, spraying the exposed layer with water may be sufiicient to remove the undecornposed material from the non-imaged areas, e.g. the non-light struck areas.

The diazo sulfonate derivates RR:N-SO H H NR are prepared by reaction of the alkali metal diazo sulfonates (RR=NSO +alkali metal) with aqueous solutions of salts of suitable organic bases, preferably in the form of the hydrochlorides of thebases. The diazo sulfonate derivatives which are easily soluble in organic solvents,rand dimcultly soluble or completely insoluble in 5 water, separate from the reaction solution as a yellow colored precipitate and can be purified by recrystallization from organic solvents. By the influence of light they are turned into compounds which, contrary to the lightsensitive diazo sulfonate derivatives themselves,cannot be retransformed into water-soluble alkali'sulfonate derivatives by means of dilute alkaline solutions and cannot be hydrolized by treating them with water. Thus, a selective separation of the relatively chemically inactive light decomposition products from the undecomposed diazo sulfonic acid salts can be attained by treating the exposed layer with water or a dilute alkaline solution.

I have not been able'to ascertain with certainty the kind of reaction that leads to the formation of the light decomposition product. It can probably be assumed that un- ,der the influence of light the diazo sulfonate derivative is first turned into a compound which is capableof coupling. If diazo sulfonate derivates are used which contain an organic base as a salt-forming component that is capable of coupling, dyes are formed in the exposed areas. These dyes are identical with the azo dyes formed by coupling salt-forming bases With the diazo compounds from which n the sulfonates are derived. Thus, images of a deep blue or red color aIeobtainedL g The formation of colored images upon exposing the light-sensitive material, according to the present invention, is of considerable technical interest since the exposing step as Well as the developing step can be easily observed by Watching the increasing coloring in the exposed areas. Heretofore, colored images could be obtained '7 from cliazo sulfonates suitable for reproduction only by adding azo components or complete dyes to the diazo sulfonates.

The following compounds are discussed in further detail in the examples.

O-NgsOHH-NH2-GO-NHTHOzSNFfiO N V N t a 1'1 -NESOQn-NHZ-O O \g/ (kCgHs O CgHs I (i) C 115 OCgHs Examples of 70 cm. A weakly blueish colored positive image becomes visible against a greenish yellow background. To develop the image, the foil is wiped over with a cotton swab soaked in a 1-10 percent trisodium phosphate solution; theunchanged yellow diazo sulfonate derivative is thereby removed in the unexposed areas. The foil is then rinsed with water, and the image side is further "pattern, using an 18 amp. carbon are lamp at a distance The compound corresponding to Formula 1 is prepared as follows: 1

2.97 parts by Weight mol) of the sodium diazo sulfonate of 3-amino-carbazole are dissolved in 250 parts by volume of water, and to this solution is added, drop by drop, a solution prepared by dissolving While stirring 1.29 parts by weight /go mol) of benzidine-hydrochloride in 55 parts by volume of water. The benzidine salt thus formed is almost insoluble in water and precipi tates in the form of green-yellow crystals. The yield, after drying, is 82.5 percent of the theoretical quantity. The compound melts at 185187 C. with decomposition.

In the same way, and with equally good results, printing plates may be produced by means of compounds prepared by analogy to the preparation of the compound corresponding to Formula 1 from the sodium diazo-sulfonatc of 3-amino-carbazole and one of the bases listed in the following table:

Color of the Reaction Melting Point of the Base Product Reaction Product (with Solvent Developer Decomposition) 3,3-di.methoxy benzidine Lemon-yellow 173174 Glycol monomethyl ether 2%9% trisodium phosphate soluion. 2',5' :2",5-tetramethoxy- Green-yellow ISO- after turning green" do Do.

4',4-diamiuo-triphenyl methane. fi-Aminonaphthalene Brown yellow 181-182 do 15% trisodium phosphate solution. Aniline Yellow green 157 do 1% trisodium phosphate solution or 5% disodium phosphate solution. 2 amino-carbazole (of. For- Yellow Chars at 22l223 0. turns Ethylene glycol mono- Water or 0.5l% solution of tri-' 'mula 2). brownbeginningat 0. methyl ether. sodium phosphate. 7

treated with a 1 percent phosphoric acid solution. On

. inking with greasy ink, ink adheres to the positive image left on the foil, and the foil may now be used as a printing plate in a printing apparatus.

with decomposition) and 0.2 part by weight of a non- ,hardenable, alkali-soluble formaldehyde-phenol-resin are T dissolved in 100 parts by volume of glycol monomethyl ether. An aluminum foil, having a mechanically roughened surface on one side, is coated with this solution by After exposure of the foil, the

analogy to Example 1. image is developed with a 2-10 percent 'trisodium phosphate solution. A positive printing plate is obtained from a negative original.

The compound corresponding 'to "Formula 3 is prepared as follows:

4.2 grams of the diazo sulfonate sodiu-nisaltof the 10.

2,5,4-triethoxy-4-amino-diphenyl are dissolved in 400 cc.

of water while mechanically agitating.

grams of 4,4-diamino-diphenyl-dihydrochloride in 150 cc.

The diamino-diphenyl salt of the diazo sulfonate precipitates as a yellow substance. After recrystallization from a dimethyl formamide/ water mixture, it melts at 160l65 C. with decomposition.

Color of the Reaction Melting Point of the Base Product 7 Reaction Product (with Solvent Developer Decomposition) -p-Diamino-diphenyl Eggyolk yellow 150 Glycol monomethyl ether-.. 0.51% aqueous solution of trimethane. sodium phosphate.

2,5 :2 ,5-tetramethoxy- Lemonyellow 144-145- rlo 5% aqueous solution of trisodium 4,4-diamino triphenylor disodium phosphate. methane. V

o,o-Dimethoxy-p-phenylcne- Brown yellow 165 Glycol monomethyl ether/ Water of 5% aqueous solution of diamine. dimethyl formamide (1:1). disodium phosphate.

2-arnino-diphenyl-ether Straw-yellow 155-156 Glycol monomethyl ether 5% aqueous solution of disodium phosphate or 05% aqueous solution of trisodium phosphate. Benzylamine Eggyolk yellow 194 Glycol monomethyl ether/ Water.

dimethyl formamide (1 :1)

Hexahydroaniline Yellow 199200 do Do.

B-amino-carbazole (of. For Brownish yellow Starts to decompose at Ethylene glycol mono- 0.5%1% aqueous solution of trimula 6) 150 0. methyl ether. sodium phosphate.

of water, and the filtered solution is then added to a solution of 1.3 grams of 4,4-diamino-diphenyl-dihydrochloride in 120 cc. of water While mechanically agitating.

The diamino-diphenyl salt of the diazo sulfonate precipitates as a yellow substance. After recrystallization from ethanol the compound melts at 151 C. with decomposition.

Analogously, diazo sulfonate derivates are obtained from the sodium diazo-sulfonate of 2,5,4-triethoxy-4- amino-diphenyl and one of the bases listed in the following table. These diazo sulfonate'derivatives may be used, according to the present invention, as light, sensitive substances for coating metal foils.

(4) One side of an aluminum foil with a mechanically roughened surface is coated by spreading upon it a 1 percent glycol monomethyl ether solution of the compound corresponding to Formula 7 (light yellow colored; melting point 240-255 C. with decomposition, after previous darkening); The layer is allowed to dry for a while, and

is then further dried for 5 minutes at a temperature of Color of the Reaction Melting Point of the Base Product Reaction Product (with Solvent Developer Decomposition) 3, 3-dimethoxy-benzidine Yellow 134136 C Glycol mono-methyl ether/ 1% aqueous solution of tridimethyl formamide (7:3). sodium phosphate.

p-Phenylene diamine Eggyolk yellow 152 0.5% aqueous solution of trisodim phosphate. 2, 4, fi-triamino-toluene Brown-yellow 131-135" Glycol monomethyl ether Water or a 0.5% aqueous Solution of trisodium phosphate.

Q-amino-diphenylene oxide Yellow 172 C Ethylene glycol mono- 35% aqueous solution of tri- (cf. Formula 4). methyl ether. sodium phosphate.

When one of the diazo sulfonates obtained from the three last mentioned bases is used, it is. recommended that formaldehyde resin not be' added for the coating of an aluminum foil.

(3) In a manner similar to that described in Example 1, an aluminum .foil, having a mechanically roughened surface on one side, is coated with a diazo sulfonate salt corresponding to Formula 5. (egg yolk colored; turns dark when heated in excess of 155-165 C.) dissolved in a 1:1 mixture of glycol monomethyl ether and dimethyl formamide. A printing plate is obtained by exposing the sensitized foil and developing with a 5 per- I cent disodium phosphate solution. The printing plate shows a positive image, when a negative transparent original is used. The copy of the original previously formed on the foil after exposure shows grey-brown lines on a yellowish background. g

The compound corresponding to Formula 5 is prepared as follows:

4.15 grams of the diazo sulfonate sodium salt of 2,5-diethoxy-N-benzoyl-p-phenylene diamine are dissolved in 260 cc. of water and then added to a solution of 1.28

is then shortly wiped over with 1 percent phosphoric acid, whereupon the positive image thus obtained may be inked with greasy ink and used as a printing plate.

The compound corresponding to Formula 7 is prepared as follows:

2.9 grams of the diazo sulfonate sodium salt of the 2- arnino-diphenyleneoxide are dissolved in 2000 cc. of water and, while mechanically agitating, the solution is mixed with a solution of 2.2 gramsof 1-amino-2-naphthol-ethylether-hydrochloride in 150 cc. of water.

The amino-naphthol-ethyl ether salt of the diazo sulfonate precipitates as a yellow substance. After recrystallization from ethanol, to which some water was added, it

to coating on an aluminum foil. After exposure under a transparent pattern, a Weakly reddish-brown image becomes visible, which can be developed with water.

() An aluminum tape with a roughened surface is continuously coated from a feed tub with a 1 percent solution of the compound corresponding to Formula 8 (dark greenish-yellow colored; melting point 151-153 C. with decomposition) dissolved in a 1:1 mixture of isopropyl alcohol and glycol monomethyl ether. After drying, the coated roll is cut into sections, and the cuttings are then exposed as usual under transparent originals and developed by means of a 1 percent trisodium phosphate solution. Reverse images of the originals are obtained. After development, the images are treated with an aqueous solution containing 8 percent dextrine, 1 percent phosphoric acid, and 1 percent formaldehyde. They may then be inked with greasy ink and used as printing plates.

The compound corresponding to Formula 8 is prepared as follows:

3.82 grams of the diazo sulfonate sodium salt of the N-2, 6-dichloro-benzyl-p-phenylene diamine are dissolved in 140 cc. of water, and while mechanically agitating, the solution is mixed with a solution of 1.16 grams of 1,5- diamino-naphthalene-dihydrochloride in 70 cc. of water.

The diamino naphthalene salt of the diazo sulfonate precipitates as a greenish-yellow substance. After recrystallization from acetone, to which some water was added, it melts at 151153 C. with decomposition.

Instead of the compound corresponding to Formula 8, there may be used as a light sensitive substance the diazo sulfonate derivative obtained from 2 moles of the sodium diazo sulfonate of N-Z,6-dichlorobenzyl-p-phenylenediamine and 1 mole of 2,5':2",5"-tetramethoxy-4,4"- diamino-triphenyl methane (hydrochloric acid salt). This compound is of greenish-yellow color and melts at 92- 95 C. with decomposition. For the preparation of the light-sensitive layer, it is dissolved in glycol monomethyl ether. On exposing under an original, a Weakly colored yellow-brown image becomes visible, which is developed by means of a 2-5 percent trisodium phosphate solution.

In the following table, the components are listed for the preparation of further diazo sulfonate salts which may be used as light-sensitive substances, in accordance with the present invention, and lead to good printing plates:

The compounds listed in the schedule are prepared by analogy to the preparation of the compound corresponding for Formula 1 as described column 3 i.e. the sodium salts of the diazo sulfonates are caused to react with the hydrochlorides of the bases in an aqueous solution. In the following, a more detailed description is given for the compounds corresponding to Formulae 12 and 14.

1 The compound corresponding to Formula 12 is prepared as follows:

1.9 grams of the diazo sulfonate sodium salt of the 4- amino-diphenyl-amine are dissolved in cc. of water, and the mixture is then mixed with a solution of 1.3 grams of aniline-hydrochloride in8 cc. of water, while mechanically agitating. The aniline salt of the diazo sulfonate precipitates as an ochre-colored substance. After recrystallization from ethanol, to which some water was added, it melts at 158 C. with decomposition.

The compound corresponding to Formula 14 is prepared as follows:

'2.97 grams of the diazo sulfonate sodium salt of the 2,5-diethoxy-4-chloro-aniline are dissolved in 330 cc. of water and then mixed with a solution of 1.15 grams of 4,4'-diamino-diphenyl-dihydrochloride in 200 cc. of water while mechanically agitating.

The diamino-diphenyl salt of the diazo sulfonate precipitates as a brownish-yellow substance. After recrystallization from ethanol, to which some water was added, it melts at 157 C. with decomposition.

This application is a continuation of copending application Serial No. 685,408, filed September 23, 1957, which in turn, is a continuation-in-part of application Serial No. 515,784, filed June 15, 1955, and now abandoned.

It will be obvious to those skilled in the art that many modifications may be made within the scope of the present invention Without departing from the spirit thereof, and the invention includes all such modifications.

What is claimed is:

1. A presensitized printing plate comprising a metal base coated with a layer comprising a compound having the formula in whi h R and R are aryl groups, the compound being applied to the base as a solution in an organic solvent.

2. A presensitized printing plate comprising a metal Diazo Sulfonate, Color of the Melting Color of sodium salt of Base Salt Point (with Solvent Image Developer decomposition) N-p-methoxy-phenylp-Ethoxy-aniline (01. Lemon- 123 Glyeolmonomethyl Yellow 0.5% aqueous solution of p-phenylene-diamine. Formula 9). yellow. ether. brown. trisodium phosphate.

Do 2,5-dimethoxy-aniline--- Cocoa 159 d0 Bluish 2.5% aqueous solution of colored. grey. disodium phosphate. N-benzoyl-o,o- Benzidine (cf. Formula Eggyolk 183184 Glycol monomethyl Bluish red 1% aqueous solution of dibutoxy-p-phen- 10). colored. ether/(limethyl trisodium phosphate. ylene-diamine. iormamide (5:1). 4-n1ethyl-3,6- 1,5-diamino naphtha- .d0 Decomposes Glycol monomethyl do l-5% aqueous solution of dimethoxy-a-aminolane (of. Formula 11). at ether/dirnethyl trisodium phosphate or diphenylsulfide. formarnidc (3:1). 10% sodium carbonate...

Do 2,5:2,5-tetra- Greenish 125-130 Methyl ethyl ketone Yellow 1-5% aqueous solution of methoxy-l,4 yellow. turns dark. brown trisodium phosphate. diaminotriphenylmethane. p-Amino-diphenyl- Aniline (cf. Formula 12)- Ochre 158 Glycol mouomethyl do Water or 5% aqueous soluamino. her. tilont oi disodium phosp a e. N-p-toluene sulfonyl-o, p-Diamino-benzene (cf. Lemon- 172174 .do Brown Do.

o-diethoxy-p-phen- Formula 13). colored. ylene-diamine. N-p-toluene-sulfonylp-Ethoxy-am'hne Yellow 113-117 .do Yellow 'Do.

0,0-diethoxy-pbrown. phenylenediaruine. V 2,5-diethoxy-4-chloro- Benzidine (of. Formula Lemon- 157 .do Greyish 5% aqueous solution of aniline. 14). colored. blue. disodium phosphate or p 1% solution (aqueous) of trisodium phosphate. Do p-Amino-benzoie acid d0 148150 .rl Bluish red Water or 5% aqueous soluethyl ester. tiltlmt of disodium phosp a e. Do 1,2,3,4,-tetrahydro-2- Yellow 174 Ethylene glycol Yellow Water.

amino naphthalene monomethylrether. brown. (see Formula 15).

having the formula 70 3,1es,;4o1 i l r r 12 base coated with a layer comprising a compound having a the compound being applied to the base as a solution in the formula an organic solvent.

' 9. A presensitized printing plate comprising an aluminum base coated with a layer comprising a compound 5 having the formula 002m H in which R is an aryl group, the compound being applied to'the base as a solution in an organic solvent. p

3. A presensitized printing plate comprising a metal base coated with a layer comprising a compound having the V formula 00,135 the compound bemg applied to the base as a solution in an organic solvent. I 10. A presensitized printing plate comprising an alumi- V nnm base coated With a layer comprising a compound 00235 having the formula (3on3 r I r r HsC$-- 2 s 2 (IJCHa i (|)OH3 v NHi-HO SN I -s--0 (|)CH3 in which R is an arylgroup, thecompound being applied the compound being applied to the base as a solution in to the base as a solution in an organic solvent. an organic solvent. 7

4. A presensitized printing. plate comprising a metal 11. A presensitized printing plate according to claim base coated with a layer comprising a compound having 1 in-which the metal base is an aluminum sheet. the formula l2. Apresensitized printing plate comprising an alumi- 10C2H 1 num base coated with a layer comprising a compound I f 002115 T N in which R is an aryl group, the compound being applied 03H to the base as a solution in an organic solvent. 7

5. A presensitized printing plate comprising a metal rlr j H V base coated with a layer comprising a compound having the formula v OCZHS I 40 the compound being applied to the base as a solution in an organic solvent. I 13. A presensitized printing plate comprising an aluminum base coated with a layer comprising a compound having the formula OCQHE i V v in which R is an aryl group, the compound being applied to the base as a solution in an organicsolvent.

2 s i 6. A presensitized printing plate comprising an aluminurn base coated with a layer comprising a compound v 0 having the formula 502L151 -NiSO H-H N-OC NH -HSO N the compound being applied to the base as a solution in anorganic solvent. a p the compound being applied to the base as a solution in 7. A presensitized printing plate comprising an alumian organic solvent.

num base coated with a layer comprising a compound 14. A presensitized printing plate comprising an alumihaving the formula i) C 2 5 I C 2115 O O H5 O Z B the compound being applied to the base as a solution in an organic solvent. V

8. A presensitized printing plate comprising an aluminum base coated with a layer comprising a compound OCzHs $0 13 3,168,401 7 l3 l4 I num base coated with a layer comprising a compound the compound being applied to the base as a solution i having the formula 7 an organic solvent. 7

6 7 21. A presensitized printing plate comprising an aluminum base coated with a layer comprising a compound I a C OO -HN C NZSOQH.NHT 5 having the formula cans C1 NzS (ME-NH;- the compound being applied to the base as a solution in 10 B an organic solvent. 0 02115 15. A presensitized printing plate comprising an aluminum base coated with a layer comprising a compound havthe compound being applied to the base as a solution in ing the formula an organic solvent.

OCH -NH-O-N SOzH-NHP o1 I l1 NHrHOaSNaONH-OlL-Q the ccmliounii i ap p lied to the base as solutmn m 22. A process for developing a printing plate which an organic so vet}: comprises exposing a light-sensitive layer, on a metal A presensmied prmtmg platefiompnsmg an almm' base, to light under a master and treating the exposed num base coated withalayer compnsmgacompound havlayer with a Solvent selected from the group consisting mg the formula of water and a weakly alkaline solution, the layer com- HQCOC NHC N2SQ3H.NH2 OOC2H6 pnslug a compound having the formula the compound being applied to the base as a solution in R 'N N SO3H-H2NR1 an organic solvent.

17. A presensitized printing plate comprising an aluminum base coated with a layer comprising a compound having the formula in which R and R are aryl groups. 23. A process for developing a printing plate which comprises exposing a light-sensitive layer, on a metal ooiru Jonas 1 O ClHe O C 4H0 the compound being applied to the base as a solution in base, to light under a master and treating the exposed an organic solvent. layer with a solvent selected-from the group consisting 18. A presensitized printing plate comprising an alumiof Water and a weakly alkaline solution, the layer'comnum base coated with a layer comprising a compound prising a compound having the formula having the formula the compound being applied to the base as a solution in \N/ an organic solvent.

19. A presensitized printing plate comprising an alumi- 5 H num base coated with a layer comprising a compound having the formula in which R is an aryl group.

(I) CgHa I zHs A) 0 2H; G 2H5 i the compound being applied to the base as a solution in an organic solvent.

20. A presensitized printing plate comprising an aluminum base coated with a layer comprising a compound having the formula 24. A process for developing a printing plate which comprises exposing a light-sensitive layer, on a metal base, to light under a master and treating the exposed layer with a solvent selected from the group consisting coin 0 can,

prising a compound having the formula in which R is an arylgroup.

25. A process for developing a printing plate which comprises exposing a light-sensitive layer, on a ,metal 27. Aprocess for developing aprinting plate which comprises exposing a light-sensitive layer, on a metal base, to light under a master and treating the exposed layer with a solvent selected from the group consisting of water and a weakly alkaline solution, the layer com-- prising a compound having the form ula 28. A process for developing a printing plate which comprises exposing a light-sensitive layer, on a metal base, to light under a master and treating the exposed base, to light under a master and treating the exposed 20 layer with a solvent selected from the group consisting layer with a' solvent selected from the group consisting of Water and a Weakly alkaline solution, the layer comprising a compound having the formula I a v V t of water and a weakly alkalinesolution, the layer comprising a compound having the formula.

' in which R is an aryl group.

26. A process for developing. a printing plate which comprises exposing a light-sensitive layer, ona metal base, to light under a master and treating the exposed layer with a solvent selected from the group consisting 50 of water and a weakly alkaline solution, the layer comprising a compound having the formula in which R is an aryl group.

29. A process for developing a printing plate which comprises exposing a light-sensitive layer, on a metal base, to light under a master and treating the exposed layer with a solvent selected from'the group consisting 5 of water and a weakly alkaline solution, the layer comprising a compound having the formula 30. A process for developing a printing plate which comprises exposinga light-sensitive layer, on a metal base, to light under a master and treating the exposed layer with a solvent selected from the group consisting of water and a weakly alkaline solution, the layer com- "prising a compound having the formula 32. A process according to claim 22 in which the metal base is an aluminum sheet.

Noreferences cited. 

22. A PROCESS FOR DEVELOPING A PRINTING PLATE WHICH COMPRISES EXPOSING A LIGHT-SENSITIVE LAYER, ON A METAL BASE, TO LIGHT UNDER A MASTER AND TREATING THE EXPOSED LAYER WITH A SOLVENT SELECTED FROM THE GROUP CONSISTING OF WATER AND A WEAKLY ALKALINE SOLUTION, THE LAYER COMPRISING A COMPOUND HAVING THE FORMULA 